Recognition and interactions controlling the assemblies of beta barrel domains

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Protein-protein interactions are crucial for biological functions.
• Understanding the forces governing protein domain assembly is essential for predicting protein structures and functions.
• Beta-sheet structures are common motifs in protein architecture.

Purpose of the Study:

• To develop and apply a computational approach for characterizing forces in beta domain assembly.
• To investigate the interplay of electrostatic, hydrophobic, and shape complementarity in protein interactions.
• To analyze the assembly of beta barrel domains in various proteins, including Cu, Zn superoxide dismutase (SOD), immunoglobulin Fab, and tomato bushy stunt virus (TBSV) coat protein.

Main Methods:

• Utilized qualitative computer graphics to analyze molecular surfaces and buried areas.
• Characterized residue-to-residue interactions, including electrostatic, hydrophobic, and hydrophilic forces.
• Applied the method to diverse protein systems with varying numbers of interacting beta domains.

Main Results:

• Strong beta domain interactions are driven by chemical, electrostatic, and shape complementarity of buried molecular surfaces.
• Hydrophobic surface area correlates with interaction strength, while electrostatic forces play a dual role in stabilizing/destabilizing contacts.
• Analysis of TBSV revealed insights into subunit accommodation, particle expansion, and assembly pathways.

Conclusions:

• The developed computational approach provides general utility for studying protein interactions and assembly.
• Molecular surface complementarity and specific interactions dictate the stability and flexibility of protein domain complexes.
• Electrostatic interactions are key determinants of specificity and dynamics in protein assembly, particularly in viral systems like TBSV.